"I need to speak to our doctor because we prepare Rio in certain ways and he has certain treatments he has to go through.

"The procedures have been the same all season which has given him fantastic performance levels when he's playing for us."

Whilst it is not unknown for Ferdinand to play successive games - only last week he faced Chelsea in the FA Cup immediately after that Champions League defeat by Real Madrid - there has been an element of managing the number of matches he is involved in.

And, as ever, Ferguson's overwhelming priority is United.

"He has to make sure he's going to be okay in terms of the number of games he plays," said the Red Devils chief.

"We've been doing that for two years and it has worked.

"We have to consider that and Rio is considering that.

"We've detailed his training programmes and given him the treatments he needs for the various complaints he has in terms of his back and groin. So far it's worked very well.

"We have to look at all these things before Rio decides and we see what the outcome is."

Reading will again be without Adam Federici and Jimmy Kebe.

Goalkeeper Federici is still sidelined by an ankle problem, meaning third-choice Stuart Taylor will again deputise following last weekend's 2-1 defeat to Aston Villa.

That defeat prompted Brian McDermott's dismissal as manager, with the club four points from safety, and caretaker boss Eamonn Dolan will also be without winger Kebe (groin). Pavel Pogrebnyak serves the last part of his three-game ban while fellow striker Jason Roberts (hip) is likely to miss the rest of the season.

The trip to Old Trafford will be Dolan's first return to the touchline after almost a decade.

The 45-year-old spent just over a season at Exeter before moving to Reading - where he has been the academy director for eight years - and admits it will be a far cry from those days when he rubs shoulders with Ferguson.

"It will be exciting of course, he is the greatest football manager of all time," he said.

"It's the best club in the world - the way they do everything. I have great respect for everybody, but on Saturday I wont be thinking about Sir Alex. They will just be names.

"I'll be doing my best for Reading trying to get that result. I'm experienced enough to know that if we are going to have that ruthless streak we need to focus on the job."

If the omens are not good for Reading staying up Dolan can at least call on one statistic to provide hope ahead of the game.